A new coronavirus, should you care?

I doubt you have missed the news but a new virus that infects (and has so far killed one person) has just been discovered in the last few months. The virus in question is believed to be a new - never before seen in the wild - kind of virus (a new coronavirus to be more precise), so we really have little clues as to how it behaves as not much work has been done.

Schematic of a coronavirus - this new virus probably looks a lot like this. From Biowiki.

We only have two examples of human infections with this new virus to go on but despite this, the BBC and other media outlets have sparked confusion (and maybe panic) by comparing it to the 2002 SARS coronavirus (whose case fatality rate was around 10% of those over eight thousand or so people infected), which proved to be a much more deadly affair. What they probably should have compared it to is the common cold coronavirus, known as 229E - an equally valid example.

But this misses the point, it is all speculation really at this minute in time. We should really wait for the hard facts to emerge. So what do we actually know?

What's happened so far?

We first became aware of this new virus (it doesn't have a name yet - nor is there any published material on it - that's how new it is) a few months back when the Erasmus Medical Centre in the Netherlands discovered the virus in a fatal case of lung disease from a Saudi national. A couple of weeks ago, it was spotted again, this time in a Qatari citizen travelling from Saudi Arabia and Qatar. So far this man has not died (he's in intensive care in the UK) but he was suffering from 'acute respiratory syndrome and renal failure' when he was airlifted to the UK and their Health Protection Agency identified the virus. By sequencing the virus's genome, the UK team confirmed it was highly similar to the Dutch sequenced one. However, this sequence has not yet been published so we don't know how this relates to the hundreds of thousands of other coronaviruses out there.

As you can predict, with such a limited understanding of this virus there are many, many questions about it. These are important questions that ultimately impact on public health and no doubt these will be answered in the coming months.

What is a coronavirus?

These coronaviruses are rather large and encased within a fatty membrane and have a very, very large genome (around 30,000 nucleotides) made up of RNA with positive sense polarity. Encoded within this massive genome are ten genes that produce a lot more proteins due to some viral tricks. These proteins are what allow it to infect and enter cells (in this case human airway cells), replicate and make new virus particles. And of course combat the immune system at every step of the way. The genome of this new virus has yet to be published so we cant comment on how it's genes look and function.

Where did it come from?

We don't know where this virus came from nor why only now are we seeing it. There is also a chance that this virus could have always been in humans but that only due to sensitive lab tests like PCR and deep sequencing we were able to detect it. Although if it does turn out to only cause severe respiratory disease this is probably not the case. Of course the other theory is that this represents the first few infections of this virus into humans, probably emerging from an animal reservoir in the middle east. Sequencing of the virus and comparison of it's genome with other known animal coronaviruses (avian or bat?) may be able to pin point where, when and how it came to infect these two men.

How dangerous is it?

So far we know of only two cases of this virus infecting humans. N =2 is not much of a sample size to draw any meaningful conclusions. In both men, it is thought this virus caused serious episodes of respiratory disease but without understanding how many other people got infected and who presented with sub-clinical or only mild disease we can't comment on how dangerous it really is.

The HPA are aware of a number of other cases of respiratory disease in the middle east but yet these aren;t confirmed to have have anything to do with this new virus. But so far, preliminary follow up studies on the contacts of these two men have yet to pick up any cases of significant disease despite these two men being well passed the viruses incubation period and peak of infectiousness. The ability to detect whether people have been infected in the past via antibody testing will surely clear this mystery up.

What can we do about it?

Not much. There's no vaccine or no cure but remember that despite this virus kicking around for at least months/weeks, only two cases have been discovered. But anybody returning from the Middle East should be aware of any respiratory symptoms as should anyone associating with people returning from these countries. The countries in question should also be keeping a close eye on clusters of disease and the origins of the virus. Currently the virus doesn't appear to be very infectious or it is highly infectious but causes little or no detectable symptoms. Both theories would fit in with the fact that we have seen no disease in the two men's contacts.

So is it like SARS or is it more like 229E? Or something entirely different? As is often the case, only time and science will tell so lets focus on the facts and concentrate on doing important epidemiological, genetic and virology work done.

1 comment:

For another take on this virus see Vincent Racaniello's post over at Virology Blog http://www.virology.ws/2012/09/25/a-new-coronavirus-isolated-from-humans/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+VirologyBlog+%28virology+blog%29

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About Connor

Connor Bamford is a PhD student at a university in Northern Ireland, UK. He is studying the molecular biology behind how viruses infect and cause disease in humans. DISCLAIMER: the views expressed in this blog are my own and are not to be confused with those of my institution where I study, my supervisor's, my group's, my nationality, my ethnicity, my gender nor my starsign.